In recent years, a rapid increase in obesity involved in westernization of lifestyle has become a serious problem. The obesity means a state in which excessive energy is accumulated owing to excessive ingestion of calorie and a decrease in calorie consumption caused by insufficient exercise or the like, and refers to “state where excessive amount of fat tissues of body (body fat) is accumulated”. The obesity is indicated as a basis of onset of so-called lifestyle-related diseases such as diabetes, hypertension, and hyperlipidemia and so forth.
The obesity exhibits a state of accumulation of excessive body fat and a phenomenon of a body weight increase. It is reported that, when rapid reduction of a body weight is conducted to ameliorate obesity, amounts of muscles playing a role in energy consumption also reduce together with the fat, and in a case of elders, symptoms such as blood pressure disorder and injury of articulatio coxae may occur (Non-patent Document 1). In addition, for a case where reduction of the amount of fat is conducted without reducing a body weight, there is a report on exercise therapy which is expected to exert an effect of improving muscle tissues (Non-patent Document 2). As described above, in recent years, there have been made attention on methods of ameliorating obesity by inhibiting accumulation of body fat, not by reducing a body weight.
The fat tissues are grouped into subcutaneous fat which is accumulated inside of a skin and visceral fat which is accumulated around visceral organs in an abdominal cavity, which are collectively called “body fat”. It is known that obesity is classified into two types, subcutaneous fat type obesity involving accumulation of the subcutaneous fat and visceral fat type obesity involving accumulation of the visceral fat. The visceral fat accumulation particularly gives large effects on frequency of onset of complications such as abnormal metabolism and cardiovascular diseases in obesity and severity thereof.
Conventionally, it has been known that pathosis in which an individual is suffering from a combination of a plurality of lifestyle-related diseases, that is, “multiple risk factor syndrome”, significantly increases the risks of onset of arteriosclerotic disease, and concepts such as Syndrome X and metabolic syndrome have been proposed as risk factors of arteriosclerotic disease. In order to evaluate comprehensive risk and prevent of the onset of arteriosclerotic disease in those multiple risk factor syndromes, international integration of definition of metabolic syndrome and diagnostic criteria therefore were conducted (Non-patent Document 3). In the diagnostic criteria for metabolic syndrome which was proposed in Japan in April, 2005, a waist size corresponding to a visceral fat area of 100 cm2 or more is adopted as an essential item instead of a body mass index (BMI) or a body fat percentage which is generally used for indicating a level of obesity. Thus, the visceral fat accumulation has been recognized to be largely involved in the cause of metabolic syndrome.
Exercise, diet, and behavior therapies are recommended as measures for reducing body fat. However, in a case where those therapies are difficult to be carried out or continued, drug therapy or a surgery may be conducted. At present, mazindol that is an anorectic is used as a therapeutic drug for obesity, and is prescribed basically for people suffering from high levels of obesity which show BMI of 35 or more. However, mazindol not only gives side effects such as headache and dry mouth, but has a large number of problems in that mazindol has contraindication when severe dysfunctions are present in the kidney, liver, or pancreas, and cannot be administered for a long period of time because of its dependency, and the like.
Plant sterols such as β-sitosterol, campesterol, stigmasterol have been known to have a reducing effect on blood cholesterol by inhibiting absorption of the cholesterol, and there is disclosed a lipid metabolism-improving agent containing diglyceride and a plant sterol as active ingredients (Patent Document 1). Further, there are disclosed an anti-obesity agent and a lipid metabolism-improving agent containing, as an active ingredient, a cholestenone compound which is synthesized by using as a starting material the plant sterols such as β-sitosterol and campesterol, or 4-cholesten-3-one (Patent Documents 2 to 5).
As typical plants belonging to the genus Aloe of the family Liliaceae, Aloe vera (Aloe barbadenisis Miller) and Aloe arborescen (Aloe arborescen Miller var. natalensis Berger) have been known, and various effects of these plants have been reported. Specifically, it is disclosed that an Aloe extract has a preventive or ameliorating effect on obesity (Patent Document 6). In addition, there are disclosed a supplement having an effect of reducing a body weight, which contains 0.25% Aloe vera powder (Patent Document 7) and an essential oil composition for controlling a body weight, which contains Aloe vera (Patent Document 8), respectively. Further, it is reported that administration of a whole leaf of Aloe arborescens to a rat resulted in a significant decrease in a body weight depending on concentrations of Aloe arborescens (Non-patent Document 4 or 5).
[Patent Document 1] Japanese patent Laid-open NO. 2005-15425
[Patent Document 2] Japanese patent Laid-open NO. 07-165587
[Patent Document 3] Japanese patent Laid-open NO. 11-193296
[Patent Document 4] Japanese patent Laid-open NO. 2001-240544
[Patent Document 5] Japanese patent Laid-open NO. 05-170651
[Patent Document 6] Japanese patent Laid-open NO. 2000-319190
[Patent Document 7] New Zealand Patent No. 330439
[Patent Document 8] U.S. Pat. No. 6,280,751
[Non-patent Document 1] Journal of Applied Physiology, vol. 95, p. 1728-1736, 2003
[Non-patent Document 2] Journal of Applied Physiology, vol. 99, p. 1220-1225, 2005
[Non-patent Document 3] Adiposcience, vol. 2, p. 11-15, 2005
[Non-patent Document 4] Medical and Biology, 125(5), p. 189-194
[Non-patent Document 5] Bulletin of the Fujita Medical Society, 22(2), p. 153-157